#13415: Instance declarations don't recognize named wildcards -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: 8.4.1 Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Poor/confusing | Unknown/Multiple error message | Test Case: Blocked By: | Blocking: Related Tickets: #13324 | Differential Rev(s): Phab:D3332 Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj):
I might be operating under a misconception here, but isn't it impossible to properly detect wildcards in a type
What do you mean by "properly detect"? How would things be better if we did "properly detect" them? Specifically * Why will the error messages get better? Can you give an example? * Is that an argument for putting wildcards everywhere? Why should only instance declarations get the benefit of this error message improvement? * Why couldn't we just improve the error messages for `LHsSigType`? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13415#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler